// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/cancelable_callback.h"

#include <memory>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/location.h"
#include "base/memory/ptr_util.h"
#include "base/memory/ref_counted.h"
#include "base/run_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/thread_task_runner_handle.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {
namespace {

    class TestRefCounted : public RefCountedThreadSafe<TestRefCounted> {
    private:
        friend class RefCountedThreadSafe<TestRefCounted>;
        ~TestRefCounted() {};
    };

    void Increment(int* count) { (*count)++; }
    void IncrementBy(int* count, int n) { (*count) += n; }
    void RefCountedParam(const scoped_refptr<TestRefCounted>& ref_counted) { }

    void OnMoveOnlyReceived(int* value, std::unique_ptr<int> result)
    {
        *value = *result;
    }

    // Cancel().
    //  - Callback can be run multiple times.
    //  - After Cancel(), Run() completes but has no effect.
    TEST(CancelableCallbackTest, Cancel)
    {
        int count = 0;
        CancelableClosure cancelable(
            base::Bind(&Increment, base::Unretained(&count)));

        base::Closure callback = cancelable.callback();
        callback.Run();
        EXPECT_EQ(1, count);

        callback.Run();
        EXPECT_EQ(2, count);

        cancelable.Cancel();
        callback.Run();
        EXPECT_EQ(2, count);
    }

    // Cancel() called multiple times.
    //  - Cancel() cancels all copies of the wrapped callback.
    //  - Calling Cancel() more than once has no effect.
    //  - After Cancel(), callback() returns a null callback.
    TEST(CancelableCallbackTest, MultipleCancel)
    {
        int count = 0;
        CancelableClosure cancelable(
            base::Bind(&Increment, base::Unretained(&count)));

        base::Closure callback1 = cancelable.callback();
        base::Closure callback2 = cancelable.callback();
        cancelable.Cancel();

        callback1.Run();
        EXPECT_EQ(0, count);

        callback2.Run();
        EXPECT_EQ(0, count);

        // Calling Cancel() again has no effect.
        cancelable.Cancel();

        // callback() of a cancelled callback is null.
        base::Closure callback3 = cancelable.callback();
        EXPECT_TRUE(callback3.is_null());
    }

    // CancelableCallback destroyed before callback is run.
    //  - Destruction of CancelableCallback cancels outstanding callbacks.
    TEST(CancelableCallbackTest, CallbackCanceledOnDestruction)
    {
        int count = 0;
        base::Closure callback;

        {
            CancelableClosure cancelable(
                base::Bind(&Increment, base::Unretained(&count)));

            callback = cancelable.callback();
            callback.Run();
            EXPECT_EQ(1, count);
        }

        callback.Run();
        EXPECT_EQ(1, count);
    }

    // Cancel() called on bound closure with a RefCounted parameter.
    //  - Cancel drops wrapped callback (and, implicitly, its bound arguments).
    TEST(CancelableCallbackTest, CancelDropsCallback)
    {
        scoped_refptr<TestRefCounted> ref_counted = new TestRefCounted;
        EXPECT_TRUE(ref_counted->HasOneRef());

        CancelableClosure cancelable(base::Bind(RefCountedParam, ref_counted));
        EXPECT_FALSE(cancelable.IsCancelled());
        EXPECT_TRUE(ref_counted.get());
        EXPECT_FALSE(ref_counted->HasOneRef());

        // There is only one reference to |ref_counted| after the Cancel().
        cancelable.Cancel();
        EXPECT_TRUE(cancelable.IsCancelled());
        EXPECT_TRUE(ref_counted.get());
        EXPECT_TRUE(ref_counted->HasOneRef());
    }

    // Reset().
    //  - Reset() replaces the existing wrapped callback with a new callback.
    //  - Reset() deactivates outstanding callbacks.
    TEST(CancelableCallbackTest, Reset)
    {
        int count = 0;
        CancelableClosure cancelable(
            base::Bind(&Increment, base::Unretained(&count)));

        base::Closure callback = cancelable.callback();
        callback.Run();
        EXPECT_EQ(1, count);

        callback.Run();
        EXPECT_EQ(2, count);

        cancelable.Reset(
            base::Bind(&IncrementBy, base::Unretained(&count), 3));
        EXPECT_FALSE(cancelable.IsCancelled());

        // The stale copy of the cancelable callback is non-null.
        ASSERT_FALSE(callback.is_null());

        // The stale copy of the cancelable callback is no longer active.
        callback.Run();
        EXPECT_EQ(2, count);

        base::Closure callback2 = cancelable.callback();
        ASSERT_FALSE(callback2.is_null());

        callback2.Run();
        EXPECT_EQ(5, count);
    }

    // IsCanceled().
    //  - Cancel() transforms the CancelableCallback into a cancelled state.
    TEST(CancelableCallbackTest, IsNull)
    {
        CancelableClosure cancelable;
        EXPECT_TRUE(cancelable.IsCancelled());

        int count = 0;
        cancelable.Reset(base::Bind(&Increment,
            base::Unretained(&count)));
        EXPECT_FALSE(cancelable.IsCancelled());

        cancelable.Cancel();
        EXPECT_TRUE(cancelable.IsCancelled());
    }

    // CancelableCallback posted to a MessageLoop with PostTask.
    //  - Callbacks posted to a MessageLoop can be cancelled.
    TEST(CancelableCallbackTest, PostTask)
    {
        MessageLoop loop;

        int count = 0;
        CancelableClosure cancelable(base::Bind(&Increment,
            base::Unretained(&count)));

        ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, cancelable.callback());
        RunLoop().RunUntilIdle();

        EXPECT_EQ(1, count);

        ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE, cancelable.callback());

        // Cancel before running the message loop.
        cancelable.Cancel();
        RunLoop().RunUntilIdle();

        // Callback never ran due to cancellation; count is the same.
        EXPECT_EQ(1, count);
    }

    // CancelableCallback can be used with move-only types.
    TEST(CancelableCallbackTest, MoveOnlyType)
    {
        const int kExpectedResult = 42;

        int result = 0;
        CancelableCallback<void(std::unique_ptr<int>)> cb(
            base::Bind(&OnMoveOnlyReceived, base::Unretained(&result)));
        cb.callback().Run(base::WrapUnique(new int(kExpectedResult)));

        EXPECT_EQ(kExpectedResult, result);
    }

} // namespace
} // namespace base
